Neurostimulation systems may be used to deliver neurostimulation therapy to patients to treat a variety of symptoms or conditions such as chronic pain, tremor, Parkinson's disease, multiple sclerosis, spinal cord injury, cerebral palsy, amyotrophic lateral sclerosis, dystonia, torticollis, epilepsy, incontinence, or gastroparesis. A neurostimulation system delivers neurostimulation therapy in the form of electrical pulses. In general, neurostimulation systems deliver neurostimulation therapy via electrodes on stimulation leads located proximate to the spinal cord, pelvic nerves, pudendal nerve, or stomach, or within the brain of a patient. The stimulation leads may include percutaneously implanted leads or surgically implanted leads.
Neurostimulation techniques may involve stimulation leads for stimulating nerves located in the epidural region, the sacral region, and the like. Stimulation of the sacral region can provide therapy for a variety of pelvic floor disorders such as urinary control disorders, fecal control disorders, interstitial cystitis, sexual dysfunction, and pelvic pain. In particular, the organs involved in various bodily functions receive much of their control via the second, third, and fourth sacral nerves, commonly referred to as S2, S3, and S4, respectively. The sacrum, in general, is a large, triangular bone situated at the lower part of the vertebral column, and at the upper and back part of the pelvic cavity. The spinal canal runs throughout the sacrum. The sacral nerves pass through the sacrum via the anterior and posterior sacral foramina. These organs are also innervated via other nerves, such as the pudendal nerve.
Electrical stimulation of the sacral nerves, pudendal nerves, and other nerves of the pelvic floor has been found to offer relief for many pelvic floor disorders. For example, medical leads having discrete electrodes are implanted on and near the sacral nerves. An implantable pulse generator drives the electrodes with an electrical signal to stimulate the sacral nerves, and thereby restore or control bodily functions affected by pelvic floor disorders. Several techniques of electrical stimulation may be used, including stimulation of nerve bundles within the sacrum.
Successful electrical stimulation generally requires that a neurostimulation lead does not migrate from a target site following implantation. Securing a neurostimulation lead at the target site may minimize lead migration. One method for securing a neurostimulation lead in a desired location includes suturing the lead to surrounding tissue. However, suturing a neurostimulation lead may involve an invasive surgery. Another method of reducing lead migration includes the use of a tined lead, which includes a lead body with protruding tines that fixate the neurostimulation lead within tissue surrounding the lead.
U.S. patent Publication No. 20030045919 to Swoyer et al. describes an implantable medical electrical lead for stimulation of the sacral nerves. The lead described by Swoyer et al. comprises a lead body with an array of flexible tine elements to fixate the lead within a. tissue site. U.S. patent Publication No. 20020161423 to Lokhoff et al. describes a transvenous lead with an extendable distal fixation member such as a helix. The fixation member described by Lokhoff et al. may be a helix, constructed of a shape memory metal or other super-elastic material, that functions to wedge or fix the lead within a vessel. U.S. Pat. No. 6,360,750 to Gerber et al. describes implantation of leads for neurostimulation within the sacral region. Table 1 below lists documents that disclose lead systems with fixation mechanisms.
TABLE 1Patent NumberInventorsTitle20030045919Swoyer et al.Implantable medical electricalstimulation lead fixation method andapparatus20020161423Lokhoff et al.System and method for positioning animplantable medical device within abody6,360,750Gerber et al.Minimally invasive surgical techniquesfor implanting devices that deliverstimulant to the nervous system
All documents listed in Table 1 above are hereby incorporated by reference herein in their respective entireties. As those of ordinary skill in the art will appreciate readily upon reading the Summary, Detailed Description and Claims set forth below, many of the devices and methods disclosed in the patents of Table 1 may be modified advantageously by using the techniques of the present invention.